Support diff mode for netcup-dns module (#11376)

* support diff mode for netcup-dns module

* Fix issue with yaml encoding after testing

* Add changelog fragment

* Fixed: proper and robust yaml import

* Remove need for yaml import

* Show whole zone in diff for context

* Update changelogs/fragments/11376-netcup-dns-diff-mode.yml

Co-authored-by: Felix Fontein <felix@fontein.de>

* Update plugins/modules/netcup_dns.py

Co-authored-by: Felix Fontein <felix@fontein.de>

---------

Co-authored-by: Felix Fontein <felix@fontein.de>

changelogs/fragments/11376-netcup-dns-diff-mode.yml

@@ -0,0 +1,2 @@
+minor_changes:
+  - netcup_dns - support diff mode (https://github.com/ansible-collections/community.general/pull/11376).

plugins/modules/netcup_dns.py

@@ -19,7 +19,8 @@ attributes:
   check_mode:
     support: full
   diff_mode:
-    support: none
+    support: full
+    version_added: 12.3.0
 options:
   api_key:
     description:
@@ -255,12 +256,18 @@ def main():
         module.fail_json(msg="record type MX required the 'priority' argument")
 
     has_changed = False
+
+    diff_mode = module._diff
+    diff = None
+
     all_records = []
     try:
         with nc_dnsapi.Client(customer_id, api_key, api_password, timeout) as api:
             all_records = api.dns_records(domain)
             record = DNSRecord(record, record_type, value, priority=priority)
 
+            if diff_mode:
+                diff_after = all_records.copy()
             # try to get existing record
             record_exists = False
             for r in all_records:
@@ -284,28 +291,40 @@ def main():
                         if not module.check_mode:
                             all_records = api.delete_dns_records(domain, obsolete_records)
 
+                        if diff_mode:
+                            diff_after = [r for r in diff_after if r not in obsolete_records]
                         has_changed = True
 
                 if not record_exists:
                     if not module.check_mode:
                         all_records = api.add_dns_record(domain, record)
 
+                    if diff_mode:
+                        diff_after.append(record)
                     has_changed = True
             elif state == "absent" and record_exists:
                 if not module.check_mode:
                     all_records = api.delete_dns_record(domain, record)
 
+                if diff_mode:
+                    diff_after.remove(record)
                 has_changed = True
+        if diff_mode:
+            diff = dict(before=into_diffable(all_records, domain), after=into_diffable(diff_after, domain))
 
     except Exception as ex:
         module.fail_json(msg=str(ex))
 
-    module.exit_json(changed=has_changed, result={"records": [record_data(r) for r in all_records]})
+    module.exit_json(changed=has_changed, diff=diff, result={"records": [record_data(r) for r in all_records]})
 
 
 def record_data(r):
     return {"name": r.hostname, "type": r.type, "value": r.destination, "priority": r.priority, "id": r.id}
 
 
+def into_diffable(records, domain):
+    return {domain: [record_data(r) for r in records]}
+
+
 if __name__ == "__main__":
     main()